RADAR SYSTEM WITH ENHANCED PROCESSING FOR INCREASED CONTRAST RATIO, IMPROVED ANGULAR SEPARABILITY AND ACCURACY, AND ELIMINATION OF GHOST TARGETS IN A SINGLE-SNAPSHOT
A radar system with enhanced processing for increased contrast ratio, improved angular separability and accuracy, and elimination of ghost targets. The radar system is equipped with transmitters, receivers, and transmit antennas and receive antennas with respective array configurations. The radar system iteratively detects target(s) by first finding the strongest target, subtracting the estimated received signal from the detected target, and repeating the process for subsequent targets until an exit condition is reached. The enhanced processing's subtraction of estimated received signals increases the contrast ratio of detectable targets. The detection is thus refined by determining optimal azimuth, elevation, gain, and phase of each detection through a joint optimization of all detections. The subtraction and refinement aid in eliminating ghost targets by removing sidelobe signals and residual errors.
1 . A radar system comprising:
a transmitter configured to transmit radio signals;
a receiver configured to receive radio signals that include the transmitted radio signals transmitted by the transmitter and reflected from objects in an environment;
wherein the receiver is configured to perform an iterative target detection process on the received radio signals to detect successively weaker targets, wherein the receiver is configured to detect a strongest target in the received radio signals, subtract an estimated received signal from the detected target signal to calculate a residual error, and repeatedly detect a next strongest target and subtract the corresponding estimated received signal from the next detected target signal until an exit condition for ending the iterative target detection process is reached.
2 . The radar system of claim 1 , wherein the receiver is configured to receive radio signals transmitted by other radar systems, wherein the other radar systems comprise a known radar system, and wherein the transmitter and the receiver are configured for use in a robot and/or a vehicle.
3 . The radar system of claim 1 , wherein the receiver is configured to end the iterative target detection process when one of a plurality of exit conditions is reached, wherein the exit condition for ending the iterative target detection process is one of the plurality of exit conditions, and wherein a first exit condition of the plurality of exit conditions comprises a completion of a selected quantity of iterations.
4 . The radar system of claim 3 , wherein the exit condition to end the iterative target detection process provides for the detection of targets in the received radio signals that are detectable with signal strengths below a given sidelobe signal level.
5 . The radar system of claim 1 , wherein iteratively subtracting estimated received signals from detected target signals incrementally increases the contrast ratio of detectable targets.
6 . The radar system of claim 1 , wherein the receiver is configured to calculate radar data comprising increasingly smaller residual errors between an expected response of estimated detections and actual measured responses.
7 . The radar system of claim 1 , wherein the receiver is configured to perform the iterative target detection process to first perform conventional beamforming to find approximate parameters of a target and to then perform a joint estimation of target parameters for all targets for each new detection added to a detection list.
8 . The radar system of claim 7 , wherein the approximate parameters comprise azimuth/elevation angles, magnitudes, and phase of the target.
9 . The radar system of claim 7 , wherein the receiver is configured to take a ratio of a maximum conventional beamforming output to a mean conventional beamforming output and compare this ratio to a predetermined threshold and use the result as another exit condition of the plurality of exit conditions of the target detection process.
10 . The radar system of claim 7 , wherein the receiver is configured to compare a change in a residual norm between the current and prior iteration to a predefined threshold and to use the result as another exit condition of the plurality of exit conditions of the target detection process.
11 . The radar system of claim 7 , wherein the receiver is configured to compare a change in a residual norm between the current and prior iteration to a predefined threshold and the result is used as another exit condition of the plurality of exit conditions of the target detection process and to end the joint estimation.
12 . The radar system of claim 1 , wherein the receiver is configured to execute the entirety of an enhanced detection algorithm on the data collected within a single snapshot, and wherein the single snapshot is a single time-instance of radar data collection.
13 . The radar system of claim 6 , wherein the receiver is configured to modify the iterative target detection process to selectively optimize different objective functions comprising at least one of detection thresholds, number of iterations used in joint estimation, and beamforming.
14 . The radar system of claim 6 , wherein a target undetectable in the received radio signals from an antenna array configured as a non-uniform array that is detectable from an antenna array configured as a uniform array is detectable when the receiver is configured to perform the iterative detection process and is thereby operable to detect targets below its sidelobe level, such that the selected antenna array configuration is selected for a selected beamwidth and angular resolution.
15 . The radar system of claim 14 , wherein the receiver is configured to perform enhanced target detection to detect targets with signal strengths below a given antenna array's sidelobe signal levels.
16 . A radar system comprising:
a plurality of transmitters configured to transmit radio signals;
a plurality of receivers configured to receive radio signals that include the transmitted radio signals transmitted by the transmitters and reflected from objects in an environment;
wherein the receivers are configured to detect a first target and to subtract a signal contribution from the first target from a measured antenna response, and to then iteratively detect one or more additional targets with signal strengths that are weaker than the first target and which were previously undetectable before signal subtraction and subtract corresponding signal contributions from the one or more additional targets from the measured antenna response until an exit condition is reached.
17 . The radar system of claim 16 , wherein the receivers are configured to jointly optimize estimated parameters of all previous detections before each subtraction, and wherein the receivers are configured to use the joint estimation to reduce residual errors and thereby prevent ghost targets from being detected by the receivers.
18 . The radar system of claim 17 , wherein the estimated parameters comprise target azimuth, elevation, magnitude, and phase, and wherein the subtraction of the signal contribution increases a contrast ratio of detectable targets.
19 . The radar system of claim 17 , wherein the receivers are configured to jointly optimize the estimated parameters through a joint optimization of all target detections, thereby increasing the accuracy of the radar system, and wherein the target subtraction and refinement both aid in eliminating ghost targets by removing sidelobe signals and residual errors which cause ghost targets to appear.
20 . The radar system of claim 17 , wherein the receivers are configured to receive radio signals transmitted by other radar system comprising at least one known radar system, and wherein the transmitters and receivers are each configured for use in a robot and/or a vehicle.